[x64] Fix up unwind info for emitted functions.

- [x64] Track size of code within emitted functions (prolog, body, epilog).
- [x64] Don't use hardcoded prolog size in generated unwind info.
- [x64] Update URLs to MSDN documentation on UNWIND_INFO/UNWIND_CODE.

src/xenia/cpu/backend/x64/x64_backend.cc

@@ -407,13 +407,25 @@ HostToGuestThunk X64ThunkEmitter::EmitHostToGuestThunk() {
   // rdx = arg0 (context)
   // r8 = arg1 (guest return address)
 
+  struct _code_offsets {
+    size_t prolog;
+    size_t body;
+    size_t epilog;
+    size_t tail;
+  } code_offsets = {};
+
   const size_t stack_size = StackLayout::THUNK_STACK_SIZE;
+
+  code_offsets.prolog = getSize();
+
   // rsp + 0 = return address
   mov(qword[rsp + 8 * 3], r8);
   mov(qword[rsp + 8 * 2], rdx);
   mov(qword[rsp + 8 * 1], rcx);
   sub(rsp, stack_size);
 
+  code_offsets.body = getSize();
+
   // Save nonvolatile registers.
   EmitSaveNonvolatileRegs();
 
@@ -424,13 +436,26 @@ HostToGuestThunk X64ThunkEmitter::EmitHostToGuestThunk() {
 
   EmitLoadNonvolatileRegs();
 
+  code_offsets.epilog = getSize();
+
   add(rsp, stack_size);
   mov(rcx, qword[rsp + 8 * 1]);
   mov(rdx, qword[rsp + 8 * 2]);
   mov(r8, qword[rsp + 8 * 3]);
   ret();
 
-  void* fn = Emplace(stack_size);
+  code_offsets.tail = getSize();
+
+  assert_zero(code_offsets.prolog);
+  EmitFunctionInfo func_info = {};
+  func_info.code_size.total = getSize();
+  func_info.code_size.prolog = code_offsets.body - code_offsets.prolog;
+  func_info.code_size.body = code_offsets.epilog - code_offsets.body;
+  func_info.code_size.epilog = code_offsets.tail - code_offsets.epilog;
+  func_info.code_size.tail = getSize() - code_offsets.tail;
+  func_info.stack_size = stack_size;
+
+  void* fn = Emplace(func_info);
   return (HostToGuestThunk)fn;
 }
 
@@ -440,10 +465,22 @@ GuestToHostThunk X64ThunkEmitter::EmitGuestToHostThunk() {
   // r8  = arg1
   // r9  = arg2
 
+  struct _code_offsets {
+    size_t prolog;
+    size_t body;
+    size_t epilog;
+    size_t tail;
+  } code_offsets = {};
+
   const size_t stack_size = StackLayout::THUNK_STACK_SIZE;
+
+  code_offsets.prolog = getSize();
+
   // rsp + 0 = return address
   sub(rsp, stack_size);
 
+  code_offsets.body = getSize();
+
   // Save off volatile registers.
   EmitSaveVolatileRegs();
 
@@ -453,10 +490,23 @@ GuestToHostThunk X64ThunkEmitter::EmitGuestToHostThunk() {
 
   EmitLoadVolatileRegs();
 
+  code_offsets.epilog = getSize();
+
   add(rsp, stack_size);
   ret();
 
-  void* fn = Emplace(stack_size);
+  code_offsets.tail = getSize();
+
+  assert_zero(code_offsets.prolog);
+  EmitFunctionInfo func_info = {};
+  func_info.code_size.total = getSize();
+  func_info.code_size.prolog = code_offsets.body - code_offsets.prolog;
+  func_info.code_size.body = code_offsets.epilog - code_offsets.body;
+  func_info.code_size.epilog = code_offsets.tail - code_offsets.epilog;
+  func_info.code_size.tail = getSize() - code_offsets.tail;
+  func_info.stack_size = stack_size;
+
+  void* fn = Emplace(func_info);
   return (GuestToHostThunk)fn;
 }
 
@@ -466,11 +516,23 @@ extern "C" uint64_t ResolveFunction(void* raw_context, uint32_t target_address);
 ResolveFunctionThunk X64ThunkEmitter::EmitResolveFunctionThunk() {
   // ebx = target PPC address
   // rcx = context
+
+  struct _code_offsets {
+    size_t prolog;
+    size_t body;
+    size_t epilog;
+    size_t tail;
+  } code_offsets = {};
+
   const size_t stack_size = StackLayout::THUNK_STACK_SIZE;
 
+  code_offsets.prolog = getSize();
+
   // rsp + 0 = return address
   sub(rsp, stack_size);
 
+  code_offsets.body = getSize();
+
   // Save volatile registers
   EmitSaveVolatileRegs();
 
@@ -481,10 +543,23 @@ ResolveFunctionThunk X64ThunkEmitter::EmitResolveFunctionThunk() {
 
   EmitLoadVolatileRegs();
 
+  code_offsets.epilog = getSize();
+
   add(rsp, stack_size);
   jmp(rax);
 
-  void* fn = Emplace(stack_size);
+  code_offsets.tail = getSize();
+
+  assert_zero(code_offsets.prolog);
+  EmitFunctionInfo func_info = {};
+  func_info.code_size.total = getSize();
+  func_info.code_size.prolog = code_offsets.body - code_offsets.prolog;
+  func_info.code_size.body = code_offsets.epilog - code_offsets.body;
+  func_info.code_size.epilog = code_offsets.tail - code_offsets.epilog;
+  func_info.code_size.tail = getSize() - code_offsets.tail;
+  func_info.stack_size = stack_size;
+
+  void* fn = Emplace(func_info);
   return (ResolveFunctionThunk)fn;
 }